1. Field of the Invention
The present invention relates to an electron emission display, and more particularly, to an electron emission display that can solve problems of increased resistance, arc discharge, and wire disconnection at electrodes exposed on an upper part of the electron emission display.
2. Description of the Related Art
In general, electron emission devices use thermionic cathodes and cold cathodes as electron emission sources. The types of electron emission devices that use cold cathodes include a field emission devices (FEDs), a Surface Conduction Emitter (SCE) devices, Metal-Insulator-Metal (MIM) devices, Metal-Insulator-Semiconductor (MIS) devices, and Ballistic electron Surface Emitting (BSE) devices.
The FED devices are based on the principle that electrons are readily emitted due to a field emission difference in a vacuum when a material having a low work function or a high β function is used as an electron emission source. Electron emission sources formed of a material that uses molybdenum or silicon as the main material having a sharp tip, a carbon material such as graphite, a Diamond like Carbon (DLC), etc., or a nano material such as nano-tubes or nano-wires have been recently developed.
The SCE device is an electron emission source in which fine cracks are formed on a conductive thin film after the conductive thin film is formed between first and second electrodes disposed facing each other on a substrate. The SCE device is based on the principle that electrons are emitted from fine cracks, which are electron emission sources, when a current flows through a surface of the conductive thin film by supplying a voltage to the first and second electrodes.
The MIM and MIS devices are based on the principle that when electron emission sources respectively having MIM and MIS structures are formed, electrons are emitted and accelerated toward a metal having a low electron potential from a metal or a semiconductor having a high electron potential when a voltage is supplied between both metals or a metal and a semiconductor which have a dielectric layer interposed therebetween.
The BSE device is based on the principle that electrons are not dispersed but rather travel in a straight line when the size of a semiconductor is reduced to a dimension smaller than a mean free path distance of electrons in the semiconductor. The BSE device is an electron emission device that emits electrons when a voltage is supplied to an ohmic electrode and a metal thin film after an electron supplying layer comprising a metal or a semiconductor is formed on the ohmic electrode and an insulating layer and the metal thin film are formed on the electron supplying layer.
FIG. 1 is a partial exploded perspective view of a conventional electron emission display that uses an FED, and FIG. 2 is a plan view of the electron emission device of FIG. 1.
Referring to FIGS. 1 and 2, the electron emission display 100 includes a front panel 90 having a phosphor material on a front surface of an electron emission device 101, and a space formed by the front panel 90 and the electron emission device 101 is supported by spacers 60. Also, although FIGS. 1 and 2 are depicted in a partial state, the space must be maintained as a vacuum. Therefore, the space between the electron emission device 101 and the front panel 90 is sealed using a sealing member.
As depicted in FIG. 1, if the electron emission device 101 has a structure in which the electrodes are exposed on an upper surface of the electron emission device 101, the sealing member contacts the electrodes. When the sealing member contacts the electrodes, resistance in the electrodes formed in a thin film is increased. The increase in resistance in the electrodes increases an overall driving voltage of the electron emission display 101 and reduces luminescence efficiency. In particular, when the electrodes having a narrow width contact the sealing member and current flows in the electrodes, a problem of an arc discharge or a wire disconnection may result. Therefore, there is a need to develop a method to solve the increased resistance, the arc discharge, and wire disconnection problems.